Undercover police are running a network of hundreds of informants inside protest organisations who secretly feed them intelligence in return for cash, according to evidence handed to the Guardian.

They claim to have infiltrated a number of environmental groups and said they are receiving information about leaders, tactics and plans of future demonstrations.

The dramatic disclosures are revealed in almost three hours of secretly recorded discussions between covert officers claiming to be from Strathclyde police, and an activist from the protest group Plane Stupid, whom the officers attempted to recruit as a paid spy after she had been released on bail following a demonstration at Aberdeen airport last month.

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Matilda Gifford, 24, said she recorded the meetings in an attempt to expose how police seek to disrupt the legitimate activities of climate change activists. She met the officers twice; they said they were a detective constable and his assistant. During the taped discussions, the officers:

â€¢ Indicate that she could receive tens of thousands of pounds to pay off her student loans in return for information about individuals within Plane Stupid.

â€¢ Say they will not pay money direct into her bank account because that would leave an audit trail that would leave her compromised. They said the money would be tax-free, and added: “UK plc can afford more than 20 quid.”